Daniel John Debrunner wrote:

> There are two options for a function:
> 
> 1) Declare the function RETURNS NULL ON NULL INPUT, this means that if
> any parameter is NULL the result is NULL and the Java method is never
> called. There are a couple of bugs outstanding on this which will be
> fixed in 10.2.
> http://issues.apache.org/jira/browse/DERBY-479
> http://issues.apache.org/jira/browse/DERBY-1030

This works fine for me. Thanks!

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  John English              | mailto:je@brighton.ac.uk
  Senior Lecturer           | http://www.it.bton.ac.uk/staff/je
  School of Computing & MIS | "Those who don't know their history
  University of Brighton    |  are condemned to relive it" (Santayana)
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